In an exhaust turbocharger used in a diesel engine of a vehicle, a variable nozzle mechanism is widely used. The variable nozzle mechanism is disposed between an exhaust gas channel of a scroll shape formed in a turbine housing and a turbine rotor rotatably disposed at the center of the turbine housing to control the flow of the exhaust gas acting on the turbine rotor.
The variable nozzle mechanism includes a nozzle mount and a nozzle plate which are supported by nozzle supports and spaced from each other. A plurality of nozzle vanes are supported rotatably between the nozzle mount and the nozzle plate. The angle of the nozzle vanes is varied to control the flow of the exhaust gas flowing between the nozzle mount and the nozzle plate, and thereby the flow of the exhaust gas acting on the turbine rotor is controlled.
For instance, Japanese Patent No. 4885118 filed by the present applicant discloses an example of a variable-geometry exhaust turbocharger including such a variable nozzle mechanism.